> When I read the article in the light of this three-level picture of TCP, it seems to me that the "purpose" view of a system, which I take to be level 3, is ju

> When I read the article in the light of this three-level picture of TCP, it seems to me that the "purpose" view of a system, which I take to be level 3, is just one of several equally valid views, not more nor less important than the others. Not only that, but you can make some pretty bad errors of thinking if you try to impose a teleology in situations where there actually isn't one.